Apparatus and process for relieving pain and discomfort



y 1951 w. J. GARDNER ETAL 2,986,140

0: LU n l- (D J :0 LL {23 m m 2 r- 9 V g E DJ l- O Q l- E 532 o 3 4 INVENTORS z z z E Wallace J. Gardn er g m 2 Joseph C.R. Lickllder a: y P

1477M NE Y5 United States Patent APPARATUS AND PROCESS FOR RELIEVNG PAIN AND DISCOMFORT Wallace J. Gardner, Cambridge, and Joseph C. R. Licklider, Arlington, Mass; said Licklider assignor to Bolt Beranek & Newnan, Inc., Cambridge, Mass., a corporation of Massachusetts Filed Dec. 10, 1958, Ser. No. 779,365

13 Claims. (Cl. 128-1) The present invention relates to apparatus and processes for relieving a patients pain and discomfort, and, more particularly, to an effective producer of analgestic or anesthetic action resulting from a particular utilization of audible sounds.

While the invention will be described hereinafter in connection with its application to the important problem of relieving the pain and discomfort originating from dental drilling and similar operations, it will be understood that this is by way of illustrating a preferred use of the same; and that the invention may similarly be practiced wherever the results attainable therewith are desired.

Various types of analgesic and anesthetic devices have been employed throughout the years to ease the pain and discomfort of a patient subjected to dental operations and the like. Included in such prior-art techniques are the administration of nitrous oxide or other gaseous medium, the injection of novocaine or other analgesic substances, and, in more serious cases, the application of a general anesthetic. All of these techniques, however, are subject to certain risks and disadvantages, but it has been considered that techniques of administration and supervision of the patient have reduced the dangers to a minimum.

An object of the present invention, however, is completely to eliminate all such dangers and disadvantages, and yet to provide the patient with adequate relief of pain and discomfort resulting from such operations and the like. Underlying the invention is the discovery that a phenomenon, relieving pain and discomfort, takes place when acoustic energy of a particular nature is applied in a particular manner to the patients auditory sensory apparatus, thereby alleviating the necessity for injecting dangerous gaseous media into the lungs of a patient, or injecting anesthetic solutions and the like into the blood stream; both, as before stated, subject to dangers and discomforting to the patient.

It is accordingly a principal object of the invention to provide a unique process for relieving pain or discomfort.

A further object is to provide a new and improved apparatus that is particularly adapted for carrying out the pain-and-discomfort-relieving process of the present invention.

An additional object is to provide a new and improved audio signal apparatus. 7

Other and further objects will be explained hereinafter and will be, more particularly pointed out in the appended claims.

In summary, the invention resides in a process and apparatus for relieving the patients sensation of pain and discomfort, such as that originating from dental operations and the like, that embodies the production of audible sound signals, preferably substantially continuous in frequency spectrum and time and, desirably, a combination of intelligible program signals, such as music and the like, supplemented by random signals, such as noise and the like. These signals are applied during the dental operations and the like, to the ears of a patient with all 'ice other sounds substantially masked from the said ears. The amplitude level of the signal is adjusted to a value that is at least suflicient to relieve the patients sensation of pain and discomfort, as a result of the phenomenon underlying the present invention.

The invention will now be described in connection with the accompanying drawing, the single figure of which illustrates a preferred apparatus for practicing the present invention.

A patient 1 is shown undergoing a dental operation, such as the application of a drill 5 to the teeth of the patient. It has been discovered, as before indicated, that if the patient receives, in a particular manner, certain audible sound signals, or combinations of signals, with all other sounds appropriately masked, the patient does not experience the pain and discomfort normally attendant upon the drilling or other operations carried out by the dentist in the patients mouth.

While it is not, of course, necessary that a correct theory be advanced for the workings of the present invention, it being sufiicient merely to describe the invention as it has been found to work in practice, the following theoretical explanation appears probably to be correct. If a relaxing intelligible program, such as music and the like, is generated in, for example, an electric, generator such as a magnetic tape reproducing apparatus 7, or other source of audible sound signal, and is fed, as later described, to appropriate sound reproducing ear phones 17, 17, applied to the ears of the patient 1, the patient may generally be lulled into a relaxed condition prior to receiving the dental drill 5. In such relaxed condition, the patient does not obtain so massive a pain sensation from a given amount of stimulation at the teeth; so that the relaxed state of the patient, even of itself, has been found to decrease the amount of pain and discomfort that is experienced. When the dentist begins to drill, however, and the sound and vibration'associated with the drilling operation is immediately evident to the patient, the patient becomes tense. It appears to be the apprehension and anxiety resulting from such tension that produces a good part of the sensation of pain and discomfort. The present invention, therefore, provides for the diverting or masking of the sensation that normally accrues to pain by injecting into the earphones17, 17", a

masking audible sensation that, in effect, floods the nervous system and tends to attach to itself an appreciable sensation that normally accrues to the pain. By insuring that the earphones 17, 17' have peripheral flanges F that fit tightly over the ears, outside sounds are effectively occluded from the ears. Both of the before-mentioned phenomena of masking all other external sounds, including the sound of the drill, and the drawing away of the peripheral part of the pain sensation through the injection of a flood of acoustic energy, result in the patients ability to endure drilling operations and the like with minimal pain and discomfort.

It has been found that, for best results, the acoustic energy should have substantially a continuous frequency spectrum and should be substantially continuous in time. The music or other signals from the source 7, moreover, should generally be supplemented with noise or random acoustic signals, as from a further sourceor generator 2, which like source .7 may be a well known electric generator of such signals. The patient 1, through controlling the relative amplitudes of the intelligible signal and the random flooding signal, at will, may adjustthe sound level to a value at which he finds the pain and discomfort of the operation to be minimal and entirely bearable;

Since the time that a patient spends in a dental chair is quite limited, acoustic energy of even very high intensity can be tolerated by the patient without damage to his auditory system and without discomfort. The patient, moreover, through his own control of the sound level, has been found automatically to adjust the same to the minimal value at which his nervous system is sufliciently flooded with the sound energy to mask the pain and discomfort of the operation as required during the application of the pain or discomfort producing stimulus. Levels of the order of the sensation of tickle, somewhat around 130 decibels above .0002 microbar, may be required by some patients; whereas, other patients have been found to find pain and discomfort adequately reduced with lower levels of the order of 100 decibels, more or less. Actually, except for very few people, it has been found that acoustic energy above substantially 120 decibels need not be employed.

In a series of controlled experiments with a large number of dental patients, it was found that the present invention, in over ninety percent of the cases, proved an effective analgesic or anesthetic; and this, even in the case of patients who had a history of receiving inadequate relief from novocaine and the like. Some patients were sufiiciently relieved of pain and discomfort through increase of the amplitude level of music having a substantially continuous pattern in both frequency and time. The majority of the patients required the simultaneous introduction of appreciable quantities of the noise energy, preferably under their own control, in order to obtain adequate relief of the pain and discomfort associated with the drilling and other dental operations. treated with the audio anesthetic of the present invention salivate noticeably less and they do not persistently resist the dentists activities by the customary forward movement of the tongue. Some patients fall asleep, while others appear to respond to this technique with lesser degrees of anesthesia. All patients, moreover, have thus far reported a complete lack of post-drilling or other post-operative sensitivenessywhereas a large percentage of patients subjected to the same operations, but with gas or novocaine and the like, report subsequent sensitiveness in the operation zone.

It was found, furthermore, that the dentist can drill much faster with the aid of the audio treatment than he can without it. Several cavities, for example, were filled in the time that it customarily took to fill one cavity, and with the patient unaware of discomfort or pain. The invention has been found to be remarkably adaptable for use with chlidren, and the like; and even, particularly,

those children who had a dread of the dental chair and were extremely tense and unruly in the past.

While, as before stated, the invention has been particularly described in connection with the important problem of dental drilling, it is of much more general application. As other typical, though by no means all-inclusive illustrations, teeth have been extracted from patients subjected to the audio anesthetic of the present invention, without pain and discomfort; and patients with headaches have reported the disappearance of the headache after receiving the audio anesthetic.

A preferred and particularly adaptable apparatus for administering the audio anesthetic of the present invention embodies the type of electrical circuits shown in the drawings.

The music or other source of preferably intelligible information is fed from the reproducing apparatus 7, such as the before-mentioned tape recorder, along two preferably stereo channels A and B, by conductors 9 and 9'. The conductors 9 and 9' connect through intermediately grounded relatively adjustable balancing attenuators 10, 10', to a pair of potentiometers 11, 11', the respective sliders 13 and 13' of which are shown ganged together. The sliders 13, 13 represent a patients hand control for adjusting the volume or level of the music or other intelligence information. It is, of course, to be understood thatother sound effects may similarly be applied, if de- The patients sired. In the case of chlidren, for example, animal sounds, trains, airplanes and other entertaining sounds may be employed.

The noise generator 2 is connected through a filter 3, that selects the predetermined band of noise frequencies to be employed, and by conductors 4 and 4 to similar relatively adjustable attenuators 12, 12, that, in turn, connect to potentiometers 6 and 6. Sliders 8, 8 associated with potentiometers 6, 6, represent a further hand control for the patient to enable him to control the level of the noise or random sounds.

The music or other intelligible audio information is applied from the potentiometer sliders 13, 13' by conductors 15, 15 to respective mixing resistors R and R Output conductors 14, 14', feeding the noise signals from the sliders 8, 8, similarly connect with respective mixing resistors R and R The mixing resistors R and R have a common terminal P, and the resistors R and R similarly share a common terminal P. In the event that the music or other audio information is of too high fidelity or quality (which has been found to disturb some patients), spoiler circuits, such as the by-pass capacitors C, C may be introduced at points P and P, as by operating the switch S to its lower or ground position, in order to limit the band or frequency response of the signals ultimately applied to the earphones 17 and 17. The earphones may incorporate conventional transducers for producing sound signals corresponding to the electrical signals from the mixing resistors and serve to direct the sound signals bilaterally into the patients auditory system. When stereo reproduction is desired, as aforesaid, the earphones produce dilferent stereo sound signal components from the corresponding different electrical signals applied thereto.

It has been found that when the noise controls 8, 8' are adjusted to produce a low level of noise, this is sometimes accompanied by leakage into the music channels. To avoid this interaction effect, the controls 8, '8' may be ganged to a switch 8;, as shown as G. The sliders 8, 8' will close the switch S when they are at their minimal positions. When the switch S is closed, energy is fed through the transformer 23 to energize a solenoid 25, thus to move its conventionally grounded contactor armature 27 downward, closing the contacts 29. Closure of the contacts 29 connects through conductors 31 and 31' to the before-mentioned conductors 14 and 14', thereby short-circuiting the output of the noise generator 2 that is fed to the mixing resistors.

When it is desired to have a dentist communicate with the patient, who, of course, in accordance with the present invention, has all external sounds masked by the appropriate earphones 17, 17', a switch S is closed. This energizes a motor M from a transformer 33. The motor M will then control, through a gang connection 35, the position of sliders 19, 19 upon respective potentiometers R and R As the resistances of potentiometers R and R are thus introduced in circuit with respective conductors 117' and 117 emanating from terminals P and P, respectively, the output of the mixer network R R R R will he attenuated. Greatly reduced output signals will thus be applied by conductors 21' and 21 to amplifiers A and A, which in turn, energize the respective earphones 17' and 17. The motor M is provided with a conventional limit cam, not shown, for stopping the position of the potentiometer sliders 19, 19' at the appropriate point. The operation of the motor M may simultaneously close a further switch S to connect a microphone 37 by conductor 39, schematically shown connected to both of the amplifiers A and A for this condition. The dentist may then communicate with the patient through the microphone 37. When switch S is opened, the sliders 19, 19' may be spring-returned (or otherwise) to their original positions, opening switch S and disconnecting the microphone circuit. The return of the potentiometer sliders 19, 19' to the upward positions illustrated, will serve to remove the attenuating resistors R tnd R from the conductor path 117, 21 and 117, and 21, thus restoring the full volume of the output of the mixer circuit R R R R to the amplifiers A and A and the earphones 17, 17'.

Further modifications will occur to those skilled in the art, and all such are considered to fall within the spirit and scope of the invention as defined in the appended claims.

'What is claimed is:

1. Apparatus of the character described having, in combination, means for producing audible sound signals comprising a mixture of intelligible sound signals, such as music and the like, and random sound signals, such as noise and the like, means for directing the said audible sound signals into the auditory system of a patient and for masking therefrom substantially all other sounds, adjustable means for controlling the relative amplitude levels of the intelligible sound signals and the random sound signals, means for reducing the level of the said sound signals directed into the patients auditory system, and means operable in response to the reducing means for directing signals from a further sound source into the said auditory system of the patient.

2. Apparatus of the character described having, in combination, electric generator means of signals of an intelligible nature, such as music and the like, electric generator means of random signals, such as noise and the like, means connected to both generator means for mixing the generated signals, means for producing sound signals corresponding to the mixed signals and for directing the sound signals into the auditory system of a patient, means for masking firom the said auditory system substantially all other sounds, adjustable means for controlling the amplitude level of the sound signals directed into the patients auditory system, means for reducing the level of the said sound signals directed into the patients auditory system, and means operable in response to the reducing means for connecting a further signal source to the said producing means, the controlling means comprising means for adjusting the relative amplitudes of the intelligible and random sound signals.

3. Apparatus as claimed in claim 2 and in which means is provided, operable when the said electric generator means of random signals is adjusted to low output level, for preventing the application of the said random signals to the said mixing means.

4. Apparatus as claimed in claim 2 and in which the output of the mixing means comprises a pair of different mixed signals and the said producing means produces therefrom a pair of different corresponding sound signals.

'5. A process for relieving a patients sensation of pain or discomfort originating from a pain-or-discomfort producing stimulus to which the patient is subjected, that comprises, producing audible sound signals substantially continuous in frequency spectrum and time and comprising noise sound signals, applying said audible sound 6 signals to the auditory system of the patient during the subjection of the patient to the stimulus, masking all other sounds from said auditory system, and increasing the amplitude level of said noise sound signals at least to a level substantially decibels above .0002 microbar for a period at least substantially commensurate with the duration of the stimulus, whereby said sensation of pain or discomfort resulting from said stimulus is relieved.

6. The process of claim 5, and in which said patient is a dental patient.

7. The process of claim 5, and in which said sound signals are applied to said auditory system bilaterally.

8. A process for relieving a patients sensation of pain or discomfort originating from a pain-or discomfort producing stimulus to which the patient is subjected, that comprises, producing audible sound signals substantially continuous in frequency spectrum and time and comprising noise sound signals and intelligible sound signals, such as music, applying said audible sound signals to the auditory system of the patient during the subjection of the patient to the stimulus, masking all other sounds from said auditory system, and increasing the amplitude level of at least said noise sound signals at least to a level substantailly 100 decibels above .0002 microbar for a period at least substantially commensurate with the duration of the stimulus, whereby said sensation of pain or discomfort resulting from said stimulus is relieved.

9. The process of claim 8, and in which in which said noise sound signals and said intelligible sound signals are mixed prior to application of the signals to said auditory system.

10. The process of claim 8, and in which the amplitude level of said intelligible sound signals is adjusted independently of the level of said noise sound signals.

11. The process of claim 8, and in which the amplitude levels of said intelligible sound signals and said noise sound signals are adjusted independently by said patient.

I12. The process of claim 8, in which two different audible sound signals are produced and in which said different audible sound signals are applied to opposite sides of said auditory system.

113. The process of claim 8, and in which said intelligible sound signals are applied to said auditory system initially without said noise sound signals.

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